Localization and significance of peanut agglutinin-binding sites on ependymoma cells

It has been suggested that peanut agglutinin (PNA)-binding sites in benign and malignant tissues were quite different. To clarify the difference of PNA-binding sites between benign and malignant ependymoma, PNA-binding sites are investigated on the surface membrane of tissues from benign and malignant ependymomas and cultured ependymoma cells. In four of five malignant ependymoma cases, PNA binding occurred in a diffuse cell membrane fashion or granular intracytoplasmic fashion without neuraminidase treatment. On the other hand, PNA binding was observed without neuraminidase treatment in only two of eight benign ependymoma cases. After neuraminidase treatment, all of our benign and malignant ependymoma cases evidenced PNA binding. PNA binding was clearly evident on the cell membrane of ependymoma cells which were able to express organotypic structures, that is, to form ependymal rosettes after neuraminidase treatment. Normal rat ependymal cells showed PNA binding only after neuraminidase treatment. These findings suggest that the masking of PNA-binding sites of ependymoma cells by sialic acid may be correlated with tumor cell differentiation.